polymorphic_routes.rb

   1 module ActionController
   2   # Polymorphic URL helpers are methods for smart resolution to a named route call when
   3   # given an Active Record model instance. They are to be used in combination with
   4   # ActionController::Resources.
   5   #
   6   # These methods are useful when you want to generate correct URL or path to a RESTful
   7   # resource without having to know the exact type of the record in question.
   8   #
   9   # Nested resources and/or namespaces are also supported, as illustrated in the example:
  10   #
  11   #   polymorphic_url([:admin, @article, @comment])
  12   #
  13   # results in:
  14   #
  15   #   admin_article_comment_url(@article, @comment)
  16   #
  17   # == Usage within the framework
  18   #
  19   # Polymorphic URL helpers are used in a number of places throughout the Rails framework:
  20   #
  21   # * <tt>url_for</tt>, so you can use it with a record as the argument, e.g.
  22   #   <tt>url_for(@article)</tt>;
  23   # * ActionView::Helpers::FormHelper uses <tt>polymorphic_path</tt>, so you can write
  24   #   <tt>form_for(@article)</tt> without having to specify <tt>:url</tt> parameter for the form
  25   #   action;
  26   # * <tt>redirect_to</tt> (which, in fact, uses <tt>url_for</tt>) so you can write
  27   #   <tt>redirect_to(post)</tt> in your controllers;
  28   # * ActionView::Helpers::AtomFeedHelper, so you don't have to explicitly specify URLs
  29   #   for feed entries.
  30   #
  31   # == Prefixed polymorphic helpers
  32   #
  33   # In addition to <tt>polymorphic_url</tt> and <tt>polymorphic_path</tt> methods, a
  34   # number of prefixed helpers are available as a shorthand to <tt>:action => "..."</tt>
  35   # in options. Those are:
  36   #
  37   # * <tt>edit_polymorphic_url</tt>, <tt>edit_polymorphic_path</tt>
  38   # * <tt>new_polymorphic_url</tt>, <tt>new_polymorphic_path</tt>
  39   # * <tt>formatted_polymorphic_url</tt>, <tt>formatted_polymorphic_path</tt>
  40   #
  41   # Example usage:
  42   #
  43   #   edit_polymorphic_path(@post)              # => "/posts/1/edit"
  44   #   formatted_polymorphic_path([@post, :pdf]) # => "/posts/1.pdf"
  45   module PolymorphicRoutes
  46     # Constructs a call to a named RESTful route for the given record and returns the
  47     # resulting URL string. For example:
  48     #
  49     #   # calls post_url(post)
  50     #   polymorphic_url(post) # => "http://example.com/posts/1"
  51     #   polymorphic_url([blog, post]) # => "http://example.com/blogs/1/posts/1"
  52     #   polymorphic_url([:admin, blog, post]) # => "http://example.com/admin/blogs/1/posts/1"
  53     #   polymorphic_url([user, :blog, post]) # => "http://example.com/users/1/blog/posts/1"
  54     #
  55     # ==== Options
  56     #
  57     # * <tt>:action</tt> - Specifies the action prefix for the named route:
  58     #   <tt>:new</tt>, <tt>:edit</tt>, or <tt>:formatted</tt>. Default is no prefix.
  59     # * <tt>:routing_type</tt> - Allowed values are <tt>:path</tt> or <tt>:url</tt>.
  60     #   Default is <tt>:url</tt>.
  61     #
  62     # ==== Examples
  63     #
  64     #   # an Article record
  65     #   polymorphic_url(record)  # same as article_url(record)
  66     #
  67     #   # a Comment record
  68     #   polymorphic_url(record)  # same as comment_url(record)
  69     #
  70     #   # it recognizes new records and maps to the collection
  71     #   record = Comment.new
  72     #   polymorphic_url(record)  # same as comments_url()
  73     #
  74     def polymorphic_url(record_or_hash_or_array, options = {})
  75       if record_or_hash_or_array.kind_of?(Array)
  76         record_or_hash_or_array = record_or_hash_or_array.compact
  77         record_or_hash_or_array = record_or_hash_or_array[0] if record_or_hash_or_array.size == 1
  78       end
  79
  80       record    = extract_record(record_or_hash_or_array)
  81       format    = extract_format(record_or_hash_or_array, options)
  82       namespace = extract_namespace(record_or_hash_or_array)
  83
  84       args = case record_or_hash_or_array
  85         when Hash;  [ record_or_hash_or_array ]
  86         when Array; record_or_hash_or_array.dup
  87         else        [ record_or_hash_or_array ]
  88       end
  89
  90       inflection =
  91         case
  92         when options[:action].to_s == "new"
  93           args.pop
  94           :singular
  95         when record.respond_to?(:new_record?) && record.new_record?
  96           args.pop
  97           :plural
  98         else
  99           :singular
 100         end
 101
 102       args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)}
 103       args << format if format
 104
 105       named_route = build_named_route_call(record_or_hash_or_array, namespace, inflection, options)
 106
 107       url_options = options.except(:action, :routing_type, :format)
 108       unless url_options.empty?
 109         args.last.kind_of?(Hash) ? args.last.merge!(url_options) : args << url_options
 110       end
 111
 112       __send__(named_route, *args)
 113     end
 114
 115     # Returns the path component of a URL for the given record. It uses
 116     # <tt>polymorphic_url</tt> with <tt>:routing_type => :path</tt>.
 117     def polymorphic_path(record_or_hash_or_array, options = {})
 118       options[:routing_type] = :path
 119       polymorphic_url(record_or_hash_or_array, options)
 120     end
 121
 122     %w(edit new formatted).each do |action|
 123       module_eval <<-EOT, __FILE__, __LINE__
 124         def #{action}_polymorphic_url(record_or_hash, options = {})
 125           polymorphic_url(record_or_hash, options.merge(:action => "#{action}"))
 126         end
 127
 128         def #{action}_polymorphic_path(record_or_hash, options = {})
 129           polymorphic_url(record_or_hash, options.merge(:action => "#{action}", :routing_type => :path))
 130         end
 131       EOT
 132     end
 133
 134     private
 135       def action_prefix(options)
 136         options[:action] ? "#{options[:action]}_" : options[:format] ? "formatted_" : ""
 137       end
 138
 139       def routing_type(options)
 140         options[:routing_type] || :url
 141       end
 142
 143       def build_named_route_call(records, namespace, inflection, options = {})
 144         unless records.is_a?(Array)
 145           record = extract_record(records)
 146           route  = ''
 147         else
 148           record = records.pop
 149           route = records.inject("") do |string, parent|
 150             if parent.is_a?(Symbol) || parent.is_a?(String)
 151               string << "#{parent}_"
 152             else
 153               string << "#{RecordIdentifier.__send__("singular_class_name", parent)}_"
 154             end
 155           end
 156         end
 157
 158         if record.is_a?(Symbol) || record.is_a?(String)
 159           route << "#{record}_"
 160         else
 161           route << "#{RecordIdentifier.__send__("#{inflection}_class_name", record)}_"
 162         end
 163
 164         action_prefix(options) + namespace + route + routing_type(options).to_s
 165       end
 166
 167       def extract_record(record_or_hash_or_array)
 168         case record_or_hash_or_array
 169           when Array; record_or_hash_or_array.last
 170           when Hash;  record_or_hash_or_array[:id]
 171           else        record_or_hash_or_array
 172         end
 173       end
 174
 175       def extract_format(record_or_hash_or_array, options)
 176         if options[:action].to_s == "formatted" && record_or_hash_or_array.is_a?(Array)
 177           record_or_hash_or_array.pop
 178         elsif options[:format]
 179           options[:format]
 180         else
 181           nil
 182         end
 183       end
 184
 185       # Remove the first symbols from the array and return the url prefix
 186       # implied by those symbols.
 187       def extract_namespace(record_or_hash_or_array)
 188         return "" unless record_or_hash_or_array.is_a?(Array)
 189
 190         namespace_keys = []
 191         while (key = record_or_hash_or_array.first) && key.is_a?(String) || key.is_a?(Symbol)
 192           namespace_keys << record_or_hash_or_array.shift
 193         end
 194
 195         namespace_keys.map {|k| "#{k}_"}.join
 196       end
 197   end
 198 end